A broad variety of uses have been developed for electrical switches which are actuable between on and off states without resort to touching. These uses are associated with safety for applications wherein the touching of a switch may lead to dangerous shorting; or health applications wherein the physically disabled may have no use of their limbs and must rely on breath to actuate a switch. Further, such switches find applications in a variety of novelty items. Particularly where light and/or breath actuated switches are concerned, the production thereof has been limited to relatively low volumes, considerations of costs and compactness not being predominant factors in this design. For example, where lights or appliances are powered from typical alternating current sources, the switching circuits which are actuated from a light source generally resort to the use of full wave rectifiers, transformers and the like to derive a direct current environment within which solid-state components may be operated to carry out switching logic. While such switching devices are effective, their weight, volume or bulk and, particularly, their cost preclude adaptation to a broad variety of applications.
One difficulty encountered in the development of lower cost light actuated switches resides in providing adequate switching sensitivity under a relatively wide range of ambient lighting conditions. Generally, it is desirable that such switching devices operate in response to the impingement thereon of relatively low intensity light; for example, the light from a common match. This light sensitivity should be operationally available while the devices remain immune to effects of a broad range of ambient lighting. Switching capability should extend from operation within a darkened room to typically encountered daylight conditions. To remain fabricable at lower costs, such switching sensitivity and ambient light immunity should be available without resort to complex ambient light compensatory circuits. Where light actuated switches can be provided which are highly compact and inexpensive while remaining adequately sensitive, a wide spectrum of new applications will be witnessed.